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Home >> Lexus >> 2009 >> LS 460 RWD >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Can Communication >> Can Communication System >> DTC U0127 Lost Communication with Tire Pressure Monitor Module >> Inspection Procedure

Inspection Procedure

  1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL 
    1. Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and the branch wire.
      CAUTION: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to prevent airbag and seat belt pretensioner activation.
      NOTE:
      • After the engine switch is turned off, the HDD navigation system requires approximately 6 minutes to record various types of memory and settings. As a result, after turning the engine switch off, wait 6 minutes or more before disconnecting the cable from the negative (-) battery terminal.
      • When disconnecting the cable, some systems need to be initialized after the cable is reconnected (see INITIALIZATION ).
  2. CHECK FOR OPEN IN CAN BUS WIRE (TIRE PRESSURE WARNING ECU BRANCH WIRE) 
    1. Disconnect the L89 tire pressure warning ECU connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      RESISTANCE REFERENCE

      Tester Connection Switch Condition Specified Condition
      L89-6 (CANP) - L89-12 (CANN) Engine switch off 54 to 69 Ω
      Fig 1: Identifying L89 Tire Pressure Warning ECU Connector Terminals
      G06198488Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      NG: REPAIR OR REPLACE TIRE PRESSURE WARNING ECU BRANCH WIRE OR CONNECTOR (CANP, CANN) 

      OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU - BATTERY AND BODY GROUND) 
    1. Connect the cable to the negative (-) battery terminal.
      NOTE: When disconnecting the cable, some systems need to be initialized after the cable is reconnected (see INITIALIZATION ).
    2. Disconnect the L89 tire pressure warning ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      RESISTANCE REFERENCE

      Tester Connection Condition Specified Condition
      L89-7 (GND) - Body ground Always Below 1 Ω
    4. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      SPECIFIED CONDITION CHART

      Tester Connection Switch Condition Specified Condition
      L89-1 (IG) - Body ground Engine switch on (IG) 11 to 14 V
      Fig 2: Identifying L89 Tire Pressure Warning ECU Connector Terminals
      G06198489Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

      OK: REPLACE TIRE PRESSURE WARNING ECU  (See REMOVAL )

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